Spur gear has teeth on the outside of a cylinder and teeth are parallel to the axis of the cylinder. This simple type of gear is the most common type its volume or the tooth usage is the largest of all types. The Shape of the tooth is that of an involute form. There are, however some notable exceptions, precision mechanical clock’s every often use. cycloidal teeth since they have lower separating loads and generally operate more smoothly than involute gears and have less tendency to bind.